some task need to start after another task, such task 7 start after task 5 finished, task 10 start after task 7 finished. if I input predecessor 5 at the task 7, then the start date of task 7 need to set the task end date + 1 if the start date of task 7 <= the end date of task 5.

how to write the EXCEL function or VBA to resolve this issue.

if the start date of task 7 changed, the following start date of tasks changed if these task have predecessor setting and need to changed if need.that is the start date and end date of task 7 changed, the task 10 may changed , if the end date of task 7 > start date of task 10.

This formula, for Item #7, in cell C8 will get you what your looking for:

=IF(E8="",DATE(2016,6,3),VLOOKUP(E8,$A$2:$D$12,4,0)+1)

This formula, for Item #10, in cell C11 will get you what your looking for:

=IF(E11="",DATE(2016,7,1),VLOOKUP(E11,$A$2:$D$12,4,0)+1)

Problem with both formulas is that you need to Hard Code a defaultdate into each formula, or you will need to put a default datesomewhere else and do a lookup to get the default date.

If possible, another way, would be to allocate a number of days to each task, then the End date is dependent on the number of days,and the Start Date of the next item is the End Date +1 of the previoustask. Something like:

The information on Computing.Net is the opinions of its users. Such
opinions may not be accurate and they are to be used at your own risk.
Computing.Net cannot verify the validity of the statements made on this
site. Computing.Net and Compnet Ventures, LLC hereby disclaim all responsibility
and liability for the content of Computing.Net and its accuracy.